#include <sys/time.h>  
#include <stdio.h>  
#include <unistd.h>  
#include <pthread.h>  
#include <errno.h>  
#include <string.h>
#include <stdlib.h>
#include <signal.h>

#define RUN 1
#define STOP 0

pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

int status = STOP;
void * thread_function(void)
{
    static int i = 0;
    while (1) 
    {   
        pthread_mutex_lock(&mut);
        while (!status)
        {
            pthread_cond_wait(&cond, &mut);
        }
        pthread_mutex_unlock(&mut);

        printf("child pthread %d\n", i++);
        if (i == 20) 
            break;
        sleep(1);
    }   
}

void thread_resume()
{
    if (status == STOP)
    {   
        pthread_mutex_lock(&mut);
        status = RUN;
        pthread_cond_signal(&cond);
        printf("pthread run!\n");
        pthread_mutex_unlock(&mut);
    }   
    else
    {   
        printf("pthread run already\n");
    }   
}

void thread_pause()
{
    if (status == RUN)
    {   
        pthread_mutex_lock(&mut);
        status = STOP;
        printf("thread stop!\n");
        pthread_mutex_unlock(&mut);
    }   
    else
    {   
        printf("pthread pause already\n");
    }
}

int main()
{
    int err;
    static int i = 0;
    pthread_t child_thread;

#if 0
    if (pthread_mutex_init(&mut, NULL) != 0)
        printf("mutex init error\n");
    if (pthread_cond_init(&cond, NULL) != 0)
        printf("cond init error\n");
#endif

    err = pthread_create(&child_thread, NULL, (void *)thread_function, NULL);
    if (err != 0 )
        printf("can't create thread: %s\n", strerror(err));
    while(1)
    {
        printf("father pthread %d\n", i++);
        sleep(1);
        if (i == 5)
            thread_resume();
        if (i == 10)
            thread_pause();
        if (i == 15)
            thread_resume();
        if (i == 20)
            break;
    }
    if (0 == pthread_join(child_thread, NULL))
        printf("child thread is over\n");
    return 0;
}
